<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		.outer {
			width: 300px;
			height: 300px;
			margin: 0 auto;
			margin-top: 100px;
			border: 1px solid black;
			/* 开启3D空间 */
			transform-style: preserve-3d;
			/* 设置景深（有了透视效果，近大远小） */
			perspective: 500px;
		}

		.inner {
			width: 300px;
			height: 300px;
			background-color: skyblue;
			transform: rotateX(30deg);
		}
	</style>
</head>
<body>
	<div class="outer">
		<div class="inner">你好</div>
	</div>
</body>
</html>